This invention relates to pressure cylinders and more particularly to pressure cylinders including means to intensify the pressure produced by the cylinders.
Pressure cylinders have been available for many years and have been employed in a multitude of work applications to perform a multitude of work operations such, for example, as piercing, punching, shape forming and resistance welding. In an effort to increase the amount of power or pressure produced by the output member of the pressure cylinder, intensifier systems have been designed for pressure cylinders in which the free end of the piston rod of a pneumatic cylinder acts against the trapped hydraulic fluid in the pressure cylinder to amplify or intensify the power produced by the output member of the pressure cylinder. Pressure cylinders of this type are shown for example in U.S. Pat. Nos. 3,875,365 and 4,099,436.
Whereas these intensifier type pressure cylinders are effective to increase the power output of the cylinder, they continue to embody certain disadvantages inherent in the basic power cylinder design. For example, they require specific anti-rotation means to preclude inadvertent rotation of the piston rod; they are in general unable to handle offset loading of the piston rod because of the limited sliding interface between the piston rod and the bore of the cylinder housing with the result that a complex and expensive guide rod mechanism is necessary to allow offset loading; the rod seal at the interface of the piston rod and the forward end wall of the cylinder experiences heavy loading and as a result requires frequent replacement; the useful life of the rod seal is further limited by debris that is introduced into the seal by the reciprocal movement of the piston rod; in situations where the piston rod is used to raise a load, the raised load must be propped up by auxiliary support means since the surface area of the piston rod is inadequate to provide a stable support platform for the raised load; and, in situations requiring a large tool mounting area on the free end of the piston, a separate mounting platform must be positioned on the free end of the piston.